Atmospheric pressure-electron capture dissociation of peptides using a modified PhotoSpray ion source.

An improved in-source atm. pressure-electron capture dissocn. (AP-ECD) method is described. Building upon the early example of Laprevote’s group, photoelectrons generated within a com. PhotoSpray atm. pressure photoionization source are used to induce ECD of multiply charged peptide ions originating from an upstream heated nebulizer device. To attain high sensitivity, the method makes use of a novel electropneumatic-heated nebulizer to assist in the creation and transmission of multiply charged ions from sample solns. Here, the authors demonstrate that readily interpretable AP-ECD spectra of infused peptides can be acquired from 100 fmol sample consumed, on a chromatog. time scale, using a conventional quadrupole time-of-flight (Q-ToF) mass spectrometer otherwise incapable of ECD/ETD expts. Though much work remains to be done to develop and characterize the method, the results indicate that AP-ECD has the potential to be a practical new total for the mass spectrometric anal. of peptides and proteins. [on SciFinder(R)]